The present invention relates generally to the field of computer graphics and, more particularly, to an anti-aliasing method for animations created or synthesized on a computer.
In synthesizing images by computers through sampling, what is called aliasing occurs. Aliasing artifacts have been troublesome in the field of graphics for a long time. These problems are particularly bad in animation sequences, since flickering thin objects and traveling jaggies are very noticeable. Conventionally, a super-sampling method is most widely used to remove aliasing of this kind (see, for example, J. Foley, et al, "Computer Graphics-Principles and Practice-," Addition--Wesley Publishing Company, 1989--hereinafter referred to as Literature 1). The super-sampling method reduces aliasing by sampling the image two or more times per pixel. To enhance the anti-aliasing effect, the super-sampling method may sometimes be used in combination with a stochastic sampling method as described in Literature 1, for example. This method slightly shifts the positions of sample points from their regular positions through use of a random number or the like, and hence permits reduction of moire-like aliasing which is caused by sampling the image at regular positions.
The above-mentioned anti-aliasing methods enhance the effect with an increase in the number of samples per pixel but pose a problem in terms of the speeding up of operation since the computational complexity and consequently the computing time also increases in proportion to the number of samples.